"The outpouring of love, gratitude and fond memories to which we've all born witness is a testament to they way a singular figure in America touched so many lives," he said.

Associated PressPresident Obama, left, and Sen. Ted Kennedy were close political allies.

First elected to the Senate in 1962, when his brother John was president, Kennedy served longer in the upper house than all but two senators in history.

"Synonymous" with the Democratic Party, Kennedy demanded respect from everyone across party lines, Obama said.

"In the United States Senate, I can think of no one who engendered greater respect or affection from members of both sides of the political aisle," he said. "His seriousness and purpose was perpetually matched by humility, warmth, good cheer and compassion. That's one reason he became not only one of the greatest senators of our time, but one of the most accomplished Americans ever to serve this democracy."